1. Technical Field
This disclosure relates to remote tracking of locks, particularly so as to allow a change in status of the lock to be detected, monitored remotely.
2. Description of the Related Art
Electronic and electromechanical padlocks that allow remote control and data logging are known in the art.
U.S. Pat. No. 6,047,575 discloses an electronic padlock having a body and shackle and a motor-operated latch assembly within the body and operable by a motor for latching and releasing the end of the shackle. An encoder is coupled to the latch assembly for moving into respective positions depending on when the end of the shackle is latched or released. A circuit within the body detects the position of the encoder and generates a signal relating to the encoder position, thus indicating whether the shackle is latched or released.
US 2008/0036596 discloses a key-operated remotely monitorable locking assembly including a key-operated lock including a body including a key operated locking assembly and a tamper monitorable lockable assembly which is selectably locked to the body by operation of the mechanical key operated locking assembly and a wireless communication circuit located in at least one of the lock body and the lockable assembly for providing a remotely monitorable indication of tampering with the lockable assembly. The arrangement shown in US 2008/0036596 relates particularly to a padlock having a flexible shackle, which is modified by providing a longitudinal bore through which a wire is passed. Opposite ends of the wire are connected to switch contacts mounted on a PCB within the padlock so as to provide an alert signal if the shackle is cut.
U.S. Pat. Nos. 4,556,872 and 5,587,702 disclose padlocks housing a tamper alarm and integral battery.
U.S. Pat. No. 5,831,531 discloses a secure lock for a shipping container in which an electrically conductive cable is anchored between the doors of the container and whose continuity is monitored by an RFID.
U.S. Pat. No. 5,046,084 discloses an electronic lock-box system configured to transmit data by fax from a central computer to a real estate office so as to allow a real estate agent to monitor access to keys of houses listed for sale.
U.S. Pat. No. 6,046,558 discloses an electronic padlock having a body and shackle and a motor-operated latch assembly for latching and releasing the end of the shackle. Security problems related to a failure of the latch mechanism are monitored using an optical encoder that provides position information to a control circuit, which correlates the position information with a signal directing power to the motor for controlling the motor remotely.
It emerges from the foregoing discussion that padlocks having integral encoders for monitoring the latching mechanism are known as is the use of such padlocks in shipping containers. However, known such padlocks are motor-operated, which gives rise to a number of potential problems such as described in U.S. Pat. No. 6,046,558. Moreover, the encoders are integrated within the padlock during manufacture, which is not only expensive but means that a regular padlock is not easily amenable to being monitored using the approaches described in the prior art.